We propose continuation of our studies of IgG oligosaccharides. Our findings indicate: 1) that IgG Fc immunoglobulin oligosaccharides are abnormal in patients with rheumatoid arthritis or systemic lupus erythematosus and 2) that IgG Fab oligosaccharides can be necessary for antibody (and autoantibody) activities. Objectives now are: 1) to define the biochemical origin and clinical significance of the IgG Fc abnormalities in rheumatoid arthritis and systemic lupus erythematosus (chemical, enzymatic and gas chromatographic techniques, clinical studies) and 2) to define the biochemical basis for an Fab sialic acid requirement in binding of certain IgG antibodies and autoantibodies (immunochemical and gas chromatographic techniques).